System Description
WARNING: This page is about a different car, the 2006 Lexus IS 350. However, it is still accessible from the selected car via links, so may be relevant.
The ECM uses signals from the output shaft speed sensor and input speed sensor to detect the actual gear position (1st, 2nd, 3rd, 4th, 5th or 6th gear).
Then the ECM compares the actual gear with the shift schedule in the ECM memory to detect mechanical problems of the shift solenoid valves, valve body or automatic transmission (clutch, brake or gear, etc.).
DTC TROUBLE DETECTION CONDITION
| DTC No. | DTC Detection Condition | Trouble Area |
|---|---|---|
| P0751 | S1 stuck ON malfunction*1
: The ECM determines there is a malfunction when the following conditions are both met. (2-trip detection logic)
|
|
| S1 stuck OFF malfunction*2
: The ECM determines there is a malfunction when the following conditions are both met.(2-trip detection logic)
|
|
HINT:
- Gear positions in the event of a solenoid valve mechanical problem:GEAR POSITIONS
ECM command gearshift 1st 2nd 3rd 4th 5th 6th *1: Actual gear position under S1 stuck ON malfunction 2nd 2nd *2: Actual gear position under S1 stuck OFF malfunction 1st 1st (1) (1) Neutral - Gear position during fail-safe operation:
If any malfunction is detected, the ECM changes into the fail-safe mode to shift into the gear positions as shown in the table below.
FAIL-SAFE MODEGear position under normal conditions 1st 2nd 3rd 4th 5th 6th *1: Actual gear position under fail safe mode when S1 stuck ON malfunction 2nd 2nd *2: Actual gear position under fail safe mode when S1 stuck OFF malfunction 1st(1) 1st(1) 3rd 3rd 3rd (1) Under engine braking downshifting to 1st or 2nd gear is prohibited.